Hypophosphatemia in Emergency Medicine Clinical Presentation

Updated: Dec 02, 2016
  • Author: Alex Koyfman, MD; Chief Editor: Erik D Schraga, MD  more...
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Presentation

History

Weakness is the most common symptom suggesting hypophosphatemia and may involve any muscular system to any extent.

  • Diplopia
  • Dysarthria
  • Dysphagia
  • Weakness of trunk or extremities, particularly the large muscle groups

Symptoms of respiratory insufficiency or myocardial depression may indicate hypophosphatemia.

Neurologic symptoms may vary, ranging from simple paresthesias to profound alterations in mental status.

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Physical

Muscle weakness is the most common physical finding; careful assessment of motor strength on neurologic examination is critical. Weakness may be subtle or profound and may involve any muscle group.

Diminished respiratory rate and tidal volume may reflect respiratory impairment due to hypophosphatemia; however, tachypnea may be present, an important clue to one of the most common etiologies of hypophosphatemia (respiratory alkalosis). [6]

Hypotension and cardiac compromise due to severe hypophosphatemia are rare.

The skin and conjunctivae may be pale secondary to the hemolytic anemia that may complicate hypophosphatemia.

Signs of rhabdomyolysis may be present on extremities including diffuse pain and weakness.

Mental status abnormalities may occur with severe hypophosphatemia, ranging from simple irritability or confusion to florid altered mental status and coma.

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Causes

The ED physician is most likely to encounter hypophosphatemia in patients withdrawing from alcohol and in patients undergoing treatment for DKA.

Other risk factors:

  • Chronic ingestion of phosphate-binding antacids
  • Patients on total parenteral nutrition (TPN) with inadequate phosphate supplementation
  • Refeeding after prolonged starvation (eg, anorexia nervosa)

Hypophosphatemia may also occur in the setting of thyrotoxic periodic paralysis (TPP). If considering this diagnosis, the presence of hypophosphatemia suggests TPP rather than spontaneous periodic paralysis, in which phosphorus levels are likely to be normal.

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